Process of treating natural alkaline waters or brines to obtain therefrom commercially useful substances



Patented May 20, 1930 UNITED STATES PATENT OFFICE JAMES G. MILLER, 01?LONE PINE, AND ALEXIS o. HOUGH'I'ON, F BARTLETT,

' CALIFORNIA PROCESS OF TREATING NATURAL ALKALINE WATERS oRiBRlNEs TOOBTAIN THERE- FROM CQMMERCIALLY USEFUL SUBSTANCES No Drawing.

The principal object of our invention relates to a method of obtainingand separating from the alkaline waters or brines of Owens Lake in InyoCounty, California, a product of sodium carbonate sufficiently separatedfrom the other constituents of the brine so that commercially usefulproductssuch as caustic soda, soda ash, sodium sesquicarbonate, orsodium bi-carbonate in a sufiicient state of purity to be acceptable tothe trade, can be manufactured therefrom. \Ve shall describe theinvention, however, more particularly as it relates to the production ofso-diu1n'carbon-\ ate suitable for the manufacture of sodium hydratecommercially known as caustic soda.

A representative brine from Owens Lake, as it exists in the intersticesof the main crystal body, and from which it may be ob tained in a clearstate by pumping, has approximately the following composition PercentNa/ OO3 NaI-IOO Q. .50

Na B O 2.50 NaCl 11.20 KOl 3.00 Nasoa, 4.71 1 .30 Na I-IPO .33

Organic matter, other salts,-and water- 65.06

Total-. 100.00 Our invention however is not limited to brines of thisparticular composition, but apin a purified'state froinbrines of thistype is thatof carbonation, which consists in passing-into the brinecarbon dioxide gas which reacts with the sodium carbonate to form sodiumbicarbonate or sodium sesquicarbonate, which substances'being lesssoluble than Application filed April 25,

1929. Serial No. 358,151.

sodium carbonate crystalize out and may be separated by filtration, andafter washing be brine contained in carbonating towers, andthe calciningof the resulting sodium bicarbonate or sodium sesquicarbonate infurnaces 1 at a relatively high temperature, which procedure involvesthe use of much'equipment or apparatus such as lime kilns, carbonatingtowers, compressors and calciners, and the purchaseof limestone, coke,and fuel oil or other fuel for the calcination.

One of the objects of our invention is to thus simplifying the processto cheapen the cost of the purified sodium carbonate.

' Another objection to the carbonation process is that owing to the factthat these brines are more or less saturated with dissolved silica, thisbeing held in solution by the degree of alkalinity of the originalbrine, when such brine is made more acid by the introduction of carbondioxide, this silica is precipitated in a gelatinous or colloidal form,rendering the precipitated sodium bicarbonate diflicult to wash freefrom the mother liquor imp-urities, and contaminating the product withsilica. 'The presence of silica in sodium carbonate intended for themanufacture of caustic soda is objectionable, as the silica reacts withthe calcium hydroxide used in causticizing to form colloidal calciumsilicate,

which hinders the settling, filtering, and washing of the calciumcarbonate mud, and when the calcium carbonate mud is reburned to produceactive lime, .as is necessary if a favorable figure for the consumptionof lime is to be obtained, this calcium silicate accumulates in thesystem to such a point as to necessitate periodically throwing out allthe lime from the process and starting with fresh lime, thus increasingthe expense.

Also the sodium metaborate in the brine is converted by carbonation intothe more inavoid the use of this equipment or apparatus,

and the purchase of this material, and by v 55 g brines the silica isseparated borate in the sodium. carbonate to be causti- I di flicult toroduce high test caustic soda su'chj cized 'over a certain low limit isobjectionable for the manufacture of caustic soda, as it oes'throughinto the finished caustic, there h lowering the NaOH content and makingit as requir by the market- Our invention avoids the contamination ofthe sodium carbonate withsilica or sodium borates.

'centigrade, the main constituent which sepa-' rates out is sodiumcarbonate decahydrate,

- rates,

-We have found that when'a brine ofthe approximate composition given is'cooled or c ed to a point not lower than zero degrees Na,CO .10H,O,with a small amount of sodium sulphate decahydrate, Na SO,.10H- O, andthat the other constituents of the brine, as sodium'and potassiumchlorides, sodium bosodium silicate, sodium phosphate, organic .matterremain dissolved in the mother liquor and may be more or less completelyse arated from the decahydrate crystals by tering ing the cryst ls withsufiicient cold water to completely displace the mother liquor con.-tained therein. It is to be understood, however, that dueto seasonalvariations in the these brines, t

' mother liquor,

' ent. In some brines-this be entirel separated they are bonate withthis. impurity by adding to the f raw brine before otassium chloridecontent of and sible to cool-as low as zero degrees centigrade withoutseparating out sodium andpotas-.

sium chloride in solid phase. We have found five degrees above zerocentigrade a goodmverage operatin temperature, but do not wish to limitourse ves to this particular temperature 'on accountof the seasonal va-'riation already mentioned.-

' We havefound further that there is a variation in the amount of NaHCO,i rrthe brine at difierent times, and that when'the alkalinity of thebrines is reduced by the separation of the more alkaline sodiumcarbonate decahydrate crease in the concentration of'NaHCO, in thecharacter and tending to recipitate .out col.- loida'l silica from the'um silicate pres- 4 separation of silica does not take place-untilafter the decahydrate cry therefore contaminate the product. In otherout during the coohng period,.and cannot fro the crystals when tered orcentrifuged and. washed. We have found that by our process it is easyand inexpensive topreventt e separationof silica an contamination of thesodium car refrigeration or refrigeration a sufficient amount of sodiumhydrate or caustic soda to and.

or centrifuging and wash-- at at times it will not be poson cooling,there results an in.

thereby I increasing its acid NaHCO NaQH Na CO H O A slight excess isused so as to keepthe brine sufliciently alkaline to prevent theseparation of silica in the mother liquor on removal of sodiumcarbonate. It is obvious, of course,

that other caustic alkalies or alkali earths, as calcium hydroxide, willefiectthe same result, and may be used in place ofor in con.-

junction with caustic soda; In this manner 'we find that it is possibleto hold all the silica permanently in solution during the cooling periodand in the separated mother liquor. By this procedure we can obtain asodium carbonate product practically free from silica. v

We also find in these brines that when there is a recipitation .ofsilica when they are acidi ed with sodium bicarbonate, carbon dioxide,or other acids, that a portion of the organic coloring matter present inthe brine is carried down by the colloidal silica and contaminates theprecipitated sodium bicarbonate or sodium carbonate product. Thepresence of this organic coloring matter is particularly objectionabledn the sodium car-' bonate to e used for the manufacture ofcaustic soda, as such organic coloring matter is completely soluble inthe caustic soda solution, and onevaporating the causticized liquor to astrength of 48% NaOH such as'is sold to the trade, the color isconcentrated and intensified and gives a deep brown caustic liquor thatis objected to. By avoiding the precipitation of silica in "our process,we find that the carrying down of organic coloring matter into theproduct is entirely prevented, such coloring matter all going throughinto the mother liquor. The decahydrate crystals if properly washed freefrom mother liquor are snow-white, and when dissolved in pure water givea water white perfectly clear so-- lution, which solution oncausticizing yields a caustic 1i uor that when evaporated down to 48% NaH is practically free from color. To give a specific example of ourinvention, 4000 cubic-centimeters of the lake brine. in which isdissolved from 5 to 20 grams of so--.

,dium hydrate, may be placed in a suitable two gallon pail or othervessel, provided with an stals are removed and does not which is keptsufliciently cooled by any of the well known refrigerating methods.

When the temperature of the lake brine has fallen to sixteen degreescentigrade, at which point crystallization may start, it is seeded withabout one gram of sodium carbonate decahydrate (Na CQ,.10H O) crystalsrespect to sodium carbonate, for if any considerable degree ofsupersaturation occurs,

.the decahydrate crystals may suddenly separate out at such a rate as tobe too small for efiicient washing and separation of the mother liquor.The cooling is continued to about five degrees centigrade at: such arate that the crystallizing period from sixteen to five degrees occupiesabout 1 to 2 hours in order to favor'the growth and building up of arelatively coarse. crystal that can be easily filtered and washed. Whenthe temperature has reached five'degrees Centigrade, the cooling isstopped and the decahydrate crystals separated from the mother liquor'by filtration, centrifuging,- or other suitable means. We prefer tocentrifuge, as this permits a rapid and eflicient removal of motherliquor before any appreciable re-solution of the crystals occurs bywarming up. When the mother liquor has been whizzed free from thecrystals, they are. washed in the centrifuge with three 200 cubiccentimeter porv tions each of ice water.

We find that from to of the sodium carbonate contained in the brine maybe recovered in the decahydrate crystals, the yield depending on theconcentration of N31360:;

originally present in the brine. We find the following to be 'a typicalanalysis of the decahydrate crystals thus produced from brine of theapproximate, composition already given. I

. Per cent Na OO .10H O 90.00 Na SO I1OI-I O 4.22 N32B2O4 -24: NaOl .31SiO .007 Na HPO s .014- Moisture (by difference) 5.209

Total 100.000

.made therefrom.

On the plant scale the brine be cooled to the desired point with anycommercial form of refrigerating apparatus, or it may I be cooled byabstraction of heat by evaporation of a portion of the water of thebrine under high vacuum, or in the winter it may be cooled by naturalmeans in outside ponds.

What we claim is: n 1. The process of separating and recovering sodiumcarbonate in a purified state from complex brines containing the samewhich consists in chilling the br1ne to a temperature above zero degreesCentigrade so as to cause the precipitation of sodium carbonatedecahydrate, and separating the decahydrate 7 crystals from the brine.

2. The process of separating and recovering sodium carbonate in apurified state from the brines of Owens Lake which consists in chillingthe brine to a temperature above zero degrees centigrade so as to causetheprecipitation of sodium carbonate decahydrate, and separating thedecahydrate crystals from the brine. 3. The process of separating andrecovermg sodium carbonate in a purified state and free from silica andorganic coloring matter from complex brines containing theseconstituents which consists in treating such brines with caustic alkaliand chilling same to a temperature above zero degrees centigrade so asto cause the precipitation of sodium carbonate decahydrate, andseparating the decahydrate crystals from the brine.

4. The process of separating and recovering sodium carbonate in apurified state and free from silica from the brines of Owens Lake whichconsists in treating such brines with caustic alkali and chilling sameto a temperature above zero degrees centigrade so as to cause theprecipitation of sodium carbonate decahydrate and separating thede- Vcahydrate crystals from the brine.

5. The process of separating and recovering sodium carbonate'in apurified state and free from organic coloring matter from the brines ofOwens Lake which consists in treating such brines with caustic alkaliand chilling same to a temperature above zero degrees centigrade so asto cause the precipitation of sodium carbonate decahydrate, andseparating the decahydrate crystals from the brine.

' 6. The process of separating and recovering sodium carbonate in apurified state from complex brines containing thesameand dis: solvedsilica which consists in adding to the brine a caustic alkali tomaintain the brine sufliciently alkaline to prevent the separation, ofsilica, then chilling the brine to cause the precipitation of sodiumcarbonate decahydrate, and then separating the decahydrate crystals fromthe brine.

7. The process of separating and'recovering sodium carbonate in apurified state from complex brines containing the same and dissolvedsilica which consists in treating the brine with a caustic alkalitomaintain it sufiiciently alkaline to prevent the separation of silicatherefrom, chilling the brine I to a temperature sufficiently low tocause the precipitation of sodium carbonate decahy drate and thenseparating the decahydrate crystals from the brine.

8. The process of separating and recovering sodium carbonate in apurified state from tals from the brine.

I pable of being -t e brine. =10. The process 9. The process ofseparating and recovering sodium carbonate in a purified state -fromcomplex brines containing the same and dissolved silica which consistsin treat' 'mg the brine with a caustic alkali to maintam it suflicientlyalkaline to prevent the sep-' aration of silica'therefrom, chilling thebrine to a point at which crystallization of sodium carbonate shouldstart, then treating said brine with seed crystals of sodium carbgnatedecahydrate to avoid su'percooling or supersaturation with respect tosodium carbonate, then continuing the cooling at a retarded rate toermit the growth of relatively coarse sodium carbonate decahydratecrystals cafiltered and washed and finalseparating the decahydratecrystals from of separating and recover- "ing sodium carbonate in apurified state from complex brines containing the same which consists inchilling the brine to ly sixteen degrees centigrade, then treating saidbrine with seed crystals of sodium carbonate decahydrate to avoidsupercooling or supersaturation with respect to sodium carbonate, thencontinuing t e coolin at a slow.-

the growth o relatively coarse crystals ca able of being filteredv andwashed. and final y se arating the decahy dratecrlyistals from the rine.

11. T e process of separating and recover ing sodium carbonate in apurified state from com lex brines containing the same which consists inchilling the brine to approximately sixteen degrees centigrade,thentreating said brine with seed crystals of sodium carbonatedecahydrate to avoid supercooling or supersaturation with respect tosodium carbonate,

Y decahydrate crystals relatively brine a caustic alkali then continuingthe cooling at a slower rate to a temperature of approximately fivedegrees centigrade to permit the growth of coarse crystals capable ofbeing filtered and washed and finally separating the from the brine.

12. The. process of separatin and recovering sodium carbonate in a puried state from complex brines containing the same and dissolved silicawhich consists in adding to the sufiiciently alkaline to prevent-theseparation t e brine to a temperadegrees centlgrade tare-ofapproximately five approximate V to maintain the brineto cause theprecipitation of sodium carbonate decahydrate, and then separating thedecahydrate crystals from the brine.

13. The process of separating1 and recovering sodium carbonate in a'puried state fromcomplex brines containing the same and dis solved silicawhich consists in treating the brine with a caustic alkali to maintainit sufiiciently alkaline to prevent the separation of silica therefrom,chilling. the brine to a temperature of approximately five degreescentigrade to cause the precipitation of sodium carbonate decahydrateand thenseparating the decahydrate crystals from the brine.- I

14. The process of separating1 ing sodium carbonate in a puri ed statefrom complex brines containing the same which consists in chilling thebrine to a temperature 9f approximately five deg as to cause theprecipitation of sodium. carbon'ate decahydrate, and separating thedecahydrate crystals from'the brine.

- 15. The rocess of'separating and recovering sodium carbonate in apurified state.

.to cause the precipitation of sodium carbonate decahydrate, and searating the decahydrate crystals from the brine. In witness whereof, wehave hereunto set our hands this 18th day of April, 1929.

JAMES G. MILLER. v

ALEXIS G. HOUGHTON.

and recover-

